Conventionally, many radial gap type motors have been used in which the gap between the stator and rotor is provided along a cylindrical surface parallel to the rotation axis for applications requiring high outputs such as a compressor, machine tool, etc. However, because of the recent higher performance of magnetic materials or the like, the study of employing an axial gap type motor in a compressor or the like has been started.
This is to respond to a request to solve the problem that a stainless pipe or the like for preventing permanent magnets from being scattered by centrifugal force increases gaps or eddy-current loss and a request to apply a plate-like magnet to a cylindrical rotor.
Patent document 6 describes that an axial gap type motor reduces axis and bearing load for compressor application. A rotor employed here has permanent magnets exposed at its surface.
Patent document 1 discloses an axial gap type motor, and employs so-called distributed winding for a stator. In a rotor employed here, permanent magnets magnetized in the axial direction are embedded in a disc part made of a non-magnetic material.
Patent document 2 discloses an axial gap type motor, and employs so-called concentrated winding for a stator. In a rotor employed here, a plurality of permanent magnets are fixed by a non-magnetic ring from their outer sides and by a magnet holder from their inner sides.
Patent document 3 discloses an axial gap type motor having magnetic poles on both sides of a rotor and stators on its both sides. In the rotor employed here, permanent magnets having a plurality of poles are disposed on both sides of a ring-shaped yoke member.
Patent document 4 discloses an axial gap type motor. In a rotor employed here, permanent magnets magnetized in the axial direction are embedded in a disc part made of a non-magnetic material.
Patent document 5 discloses an axial gap type switched reluctance motor.
Patent document 1: Japanese Patent Application Laid-Open No. 5-268754
Patent document 2: Japanese Patent Application Laid-Open No. 8-126277
Patent document 3: Japanese Patent Application Laid-Open No. 10-164779
Patent document 4: Japanese Utility Model No. 3062085
Patent document 5: Japanese Patent Application Laid-Open No. 2004-166354
Patent document 6: Japanese Patent Application Laid-Open No. 2004-52657